Battery management system and method

ABSTRACT

A battery management system for managing a plurality of subsystem circuits and functions of a mobile communication device powered by a battery is disclosed. The battery management system includes a battery monitoring circuit a user interface, and a battery management module. The battery monitoring circuit is operable to monitor a present battery capacity and generate a battery capacity signal based on the present battery capacity. The user interface is operable to receive a user-input allocation of battery capacity among the subsystem circuits and functions. The battery management module is operable to receive the user-input allocation and the battery capacity signal, and to selectively disable each subsystem circuit or function when each subsystem circuit or function has depleted its allocation of battery capacity.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 11/445,664, filed onJun. 2, 2006, which is a continuation of U.S. Ser. No. 10/688,294, filedon Oct. 17, 2003, now U.S. Pat. No. 7,057,372. The complete disclosureof these prior applications, including the drawings, is herebyincorporated into this application by reference.

BACKGROUND

1. Field of the Invention

The invention relates generally to power supply systems, and inparticular to a battery management system in a mobile communicationdevice.

2. Description of the Related Art

A typical mobile communication device is powered by a rechargeablebattery. However, the same mobile communication device may also includeseveral subsystem circuits, such as input/output (I/O) circuits,wireless communication circuits, processing circuits, and the like, tosupport such device functions as voice communication functions and datacommunication functions.

Each device function may be supported by one or more subsystem circuits.The activity period of a subsystem circuit varies according to thefunction activated at the mobile communication device. Thus, powerrequirements may vary significantly among device functions, due todifferences among the subsystem circuits supporting each function andthe activity periods of each subsystem circuit. If battery charge islow, the mobile communication device may be able to support lower powerfunctions. but unable to support higher power functions.

Given their larger current requirements, higher power functionsdischarge a battery more quickly than lower power functions, and maytherefore discharge the battery to such a low level that neither higherpower functions nor lower power functions may be used. Battery dischargerates are also affected by temperature, such that a battery oftendischarges more quickly at lower temperatures, during cold weatherconditions for example. Although surface charge of a battery mayinitially support some lower power functions, thereby to reduce coldbattery discharge at low temperatures, power requirements for higherpower functions are not significantly reduced by surface charge. Assuch, lower power functions may be preferred over higher power functionswhen a battery is at a low temperature.

Known power management systems for mobile communication devicestypically provide visual or aural indicators that a battery charge islow. Other power management systems reserve battery charge for aone-time operation of a function, such as an emergency 911 call, whenthe battery charge is low. Still other power management systems providevarious power modes dependent upon battery charge level.

SUMMARY

According to one aspect of the invention, a battery management systemmanages a plurality of subsystem circuits and functions of a mobilecommunication device powered by a battery. The battery management systemcomprises a battery monitoring circuit operable to monitor a presentbattery capacity and generate a battery capacity signal based on thepresent battery capacity, a user interface operable to receive a userinput allocation of battery capacity among the subsystem circuits andfunctions, and a battery management module operable to receive the userinput allocation and the battery capacity signal, and selectively todisable each subsystem circuit or function when each subsystem circuitor function has depleted its allocation of battery capacity.

In accordance with another aspect of the invention, a method formanaging a plurality of subsystem circuits and functions of a mobilecommunication device powered by a battery comprises allocating batterycapacity among the subsystem circuits and functions, comparing a presentbattery capacity of a battery to respective amounts of battery capacitydepleted by the subsystem circuits and functions, and selectivelydisabling each subsystem circuit or function after each subsystemcircuit or function has depleted its allocation of battery capacity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a battery management system in a mobilecommunication device;

FIG. 2 is a block diagram of one embodiment of the battery managementsystem;

FIG. 3 illustrates a hierarchical allocation of battery capacity;

FIG. 4 is a block diagram of another embodiment of the batterymanagement system;

FIG. 5 is a block diagram of another embodiment of the batterymanagement system;

FIG. 6 is a flow diagram of a battery management process based onsubsystem circuit and function battery capacity allocation;

FIG. 7 is a flow diagram of a battery management process based onsubsystem circuit and function power requirements;

FIG. 8 is a flow diagram of a battery management process based onsubsystem circuit and function enable conditions;

FIG. 9 is a flow diagram of a battery management process based onfunction threshold temperatures;

FIG. 10 is a flow diagram of a battery management process based onfunction threshold temperatures and battery chemistry;

FIG. 11 is a data structure describing the interrelation of subsystemcircuits, functions, and corresponding battery allocations,requirements, or conditions;

FIG. 12 is a display illustrating remaining allocated battery capacity;and

FIG. 13 is a block diagram of a mobile communication device.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of a battery management system 10 in a mobilecommunication device 20. The mobile communication device 20illustratively comprises a power subsystem 30 and a plurality ofsubsystem circuits S0, S1, S2 . . . Sn. Each subsystem circuit S0, S1,S2 . . . Sn supports a corresponding function set f0, f1, f2 . . . fn.The mobile communication device 20 may be realized by a data messagingdevice, a two-way pager, a cellular telephone with data messagingcapabilities, a wireless Internet appliance, or other data communicationdevices, depending on the functionality provided. An exemplary mobilecommunication device 20 is described in detail with reference to FIG. 13below.

Each function set may include common functions. Thus, one or moresubsystem circuits S0, S1, S2 . . . Sn may be activated to support acorresponding common function. For example, if the mobile communicationdevice 20 is a cellular telephone with Internet connectivity, a voicefunction fv of placing and maintaining a cellular telephone call mayrequire activation of several subsystem circuits, such as a display andkeyboard subsystem (illustratively S0), a speaker/microphone subsystem(illustratively S1), and a wireless communication subsystem(illustratively S2). Accordingly, function sets f0, f1 and f2 eachinclude the voice function fv.

A data function fd for receiving a Wireless Access Protocol (WAP) deck,however, may require activation of only the display and keyboardsubsystem S0 and the wireless communication subsystem S2. Accordingly,only the function sets f0 and f2 include the data function fd.

Additionally, a subsystem circuit S0, S1, S2 . . . Sn may have anassociated unique function. For example, if the subsystem circuit S0 isa keyboard and display subsystem, then a backlighting function may beincluded only in the function set f0.

The power requirements for each function may vary significantly, andtypically depend on which subsystem circuits are required to supporteach function and the active duration of each subsystem circuit duringthe performance of each function. To illustrate, in a standby mode inwhich no functions are being performed, a typical mobile communicationdevice draws about 0.5-1 milliamps. During the execution of functions,however, the keyboard and display subsystem S0, with backlightingactivated, draws about 200-300 milliamps; the speaker/microphonesubsystem S1 draws several milliamps; and the communication subsystem S2draws about 200-300 milliamps.

Executing a voice function fv, such as a telephone call, requires thesupporting subsystem circuits S0, S1 and S2 to be active during theduration of the telephone call. The communication subsystem S2 transmitsand receives data during the duration of the telephone call, the displayand keyboard subsystem S0 display call data, and the speaker/microphonesubsystem S0 converts between audio and electrical signals. Thus, whileperforming a voice function fv, the mobile communication device 20 maydraw from 200-300 milliamps without backlighting, and from 400-600milliamps with backlighting.

For the data function fd, however, the active period of thecommunication subsystem S2 will typically be of a much shorter durationthan during a voice function fv, as the communication subsystem S2 willtypically transmit a simple request, such as a Uniform ResourceIdentifier (URI) query, and wait to receive response data. After theresponse data is received, the user may examine the data via thekeyboard and display subsystem S0. Accordingly, the data function fdrequires much less average power than the voice function fv, as thecommunication subsystem S2 is typically active for only several hundredmilliseconds rather than the several minutes of the voice function fv.For example, when performing a data function fd without backlighting,the mobile communication device 10 will usually draw only severalmilliamps, with an occasional instantaneous demand of 200-300 milliampsfrom the communication subsystem S2.

In operation, a typical mobile communication device will notify the userof a low battery charge by either an aural or visual alarm. Often a userwill have only a short time remaining before the battery charge isdepleted to such a state that all functions are disabled, which mayinconvenience the user. For example, a user of a mobile communicationdevice having cellular telephone, e-mail, and web access functions maylearn of time-critical information during a cellular telephone call andneed to access e-mail and several web sites after the cellular telephonecall. In this case, if the user receives a low battery chargenotification during the telephone call and does not have an alternateavailable power source for the mobile communication device, the user mayneed to conserve power for the e-mail and web access data functions, bycutting the cellular telephone call short, for example. It is alsopossible that, before the user receives or becomes aware of thenotification, the battery charge has already been depleted to such adegree that the e-mail or web access data functions are inoperable untilthe battery is recharged. This precludes the user from accessing thetime-critical information.

The battery management system 10 of FIG. 1 allows a user of the mobilecommunication device 20 to allocate battery capacity among the subsystemcircuits and functions. Thus, a user may allocate a percentage ofbattery capacity (e.g., battery charge or battery time) to voicefunctions and a remaining percentage of battery capacity to datafunctions. Accordingly, when the battery capacity for voice functions isdepleted, there may still be remaining battery capacity to support thedata functions. Likewise, when battery capacity for data functions isdepleted, there may be remaining battery capacity to support the voicefunctions.

FIG. 2 is a block diagram of one embodiment of the battery managementsystem 10. The battery management system includes a battery managementmodule 100, a battery monitoring circuit 102, and a user interface 104.The battery monitoring circuit 102 is operable to provide a status ofone or more battery status indicators, such as remaining capacity,temperature, voltage, current draw, and the like. The battery statusindicators may be provided in either analog or digital form. Exemplarybattery monitoring circuits include a simple voltage monitor to measurethe battery voltage, or alternatively a voltage monitor, a currentmonitor, and a temperature monitor coupled to a digital logic circuitthat estimates a remaining battery capacity based on one or morevariables of voltage, current, and temperature. Such battery monitoringcircuits are well known in the art and are therefore not described infurther detail.

In another embodiment, a so-called “smart battery” may be used. A smartbattery includes electronic components and software that enablemeasurements and calculations of battery capacity, and communicates withother components such as a processor of the mobile communication device20. In this embodiment, the battery monitoring circuit 102 may beincorporated into the smart battery.

A user interface 104 is operable to receive a user-input allocation ofbattery capacity among the subsystem circuits and functions. The userinterface 104 may comprise a touch sensitive display, or a combinationkeyboard and display, or any other I/V circuit that provides a user acapability to input an allocation of battery capacity among thesubsystem circuits and functions. Indications of remaining allocatedbattery capacity may also be provided to a user via the user interface104, as described in further detail below with reference to FIG. 12.

The battery management module 100 is operable to receive the user-inputallocation 110 from the user interface 104 and the battery status signalfrom the battery monitoring circuit 102. It also selectively disableseach subsystem circuit or function when each subsystem circuit orfunction has depleted its allocation of battery capacity. The batterymanagement module 100 may be implemented as a stand alone module, suchas an Application Specific Integrated Circuit (ASIC) and software, oralternatively as a software program executed by an existing systemprocessor in the mobile communication device 20.

Battery capacity may be allocated based on function, supportingsubsystem circuits, or some combination thereof In one embodiment, thebattery capacity is allocated based on functions. For example, a usermay allocate a percentage of full battery charge to a voice function fv,and allocate a remaining percentage of full battery charge to a datafunction fd. Thus, the voice function fv is disabled when it hasdepleted its allocation of battery capacity. The data function fd,however, is still operable at the mobile communication device 20 if thedata function fd has not yet depleted its allocation of batterycapacity.

In this embodiment, the battery management module 100 is operable tomonitor the percentage of full battery charge expended by each function.Such monitoring may be accomplished, for example, by monitoring themilliamp-hours expended for each function performed. During theperformance of a particular function f. the battery management module100 receives a corresponding indicator related to the current providedby the mobile communication device 20 battery 30. For example, themonitoring of an average current of 250 milliamps for a 30-minutecellular telephone call would result in a monitored value of 125milliamp hours. The monitored value is then compared to the batteryrating. Accordingly, if the battery is rated at 1000 milliamp hours, thevoice function fv has depleted 12.5% of the battery charge.

Consider an illustrative example in which a voice function fv has beenallocated 60% of full battery charge and depleted 55% of the fullbattery charge, and a data function fd has been allocated 40% of fullbattery charge and depleted 5% of the full battery charge. The voicefunction fv therefore has only 5% of the full battery charge remaining,whereas the data function fd has 35% of full battery charge remaining.When the voice function fv depletes or has nearly depleted its remainingallocated battery charge, the mobile communication device 20 issues acorresponding “low battery” notification for the voice function fv onthe user interface 104. However, the mobile communication device 20still has ample power remaining for carrying out the data function fd.Thus the e-mail and web access data functions, referenced in the exampleabove, may be executed so that the user receives the time-criticalinformation.

In another embodiment, the user may allocate a percentage of totalbattery time to a voice function , and allocate a remaining percentageof total battery time to a data function fd. For example, if a mobilecommunication device 20 is rated to provide 90 minutes of continuous usefor a particular battery at full charge, then the voice function fv maybe allocated 60 minutes of battery time, and the data function fd may beallocated the remaining 30 minutes of battery time. The batterymanagement module 100 is then operable to monitor the time of use foreach function. Such monitoring may be accomplished, for example, bymonitoring a clock during the performance of each function andincrementing a function time variable associated with each function.

In a further embodiment, one function may be allocated a percentage ofbattery capacity, and the remaining functions are not subject to abattery allocation. Thus, a user may allocate a certain percentage ofbattery capacity to a particular data function, but all remainingfunctions may use up to 100% of the battery capacity either alone or incombination.

Upon determining that a particular function has depleted its allocationof battery capacity, the battery management module 100 may selectivelydisable the function. The function may be disabled while it is beingperformed (e.g., by terminating a cellular telephone call), or after thefunction is completed (e.g., after the cellular telephone call iscompleted). For example, if the voice function fv has depleted itsallocation of battery capacity, then the display and keyboard subsystemS0, the speaker/microphone subsystem S1, and the wireless communicationsubsystem S2 in FIG. 1 are precluded from performing the voice functionfv. However, the display and keyboard subsystem S0 and the wirelesscommunication subsystem S2 may still be utilized to perform the datafunction fd.

Where a particular subsystem S is solely associated with a disabledfunction f, such that the subsystem S is active only when the function fis performed, then the subsystem S may be disabled when the function fhas depleted its allocation of battery capacity. A particular subsystemmay be disabled by the activation of a solid state switch or other knownswitching or disabling methods. For example, if the subsystem S0 is aninfrared communication circuit that supports a single localcommunication function f0 which has depleted its allocation of batterycapacity, then the battery management module 100 may selectively disableboth the local communication function f0 and the infrared communicationcircuit S0.

The battery management module 100 may be further configured to monitorthe self-discharge of the battery 30 via the battery monitoring circuit102. The self-discharge may then be apportioned to each allocation ofbattery capacity either equally or according to the allocation. In theabove example of a 60%/40% allocation between a voice function fv and adata function fd, a 10% self discharge of the battery 30 after a periodof inactivity may be apportioned as 5% for each of fv and fd in an equalapportion scheme or 6% for fv and 4% for fd in a pro-rata apportionscheme.

Of course, allocations may be based on other functions instead of voicefunctions and data functions. For example. if the mobile communicationdevice 20 is operable to perform a digital communication function fvd,an analog communication function fva, an e-mail function fde, and acalendar function fc, the user may allocate battery capacity to eachindividual function.

Battery capacity may also be allocated according to a hierarchicalallocation. FIG. 3 illustrates a hierarchical allocation of batterycapacity. In the embodiment of FIG. 3, the hierarchical allocation isbased on a per-function allocation of battery capacity. However, thehierarchical allocation may also be based on subsystem circuits or acombination of subsystem circuits and functions.

In FIG. 3, f represents a set of functions that are to be controlled bya battery management system. The set of functions f may be the entireset of functions performed by the mobile communication device or asubset of those functions. The functions f are illustratively dividedinto two function subsets: voice functions fv and data functions fd. Thevoice functions fv are divided into two subsets: analog voice functionsfva, and digital voice functions fvd. Likewise, the data functions fdare divided into two subsets: e-mail data functions fde, and webbrowsing data functions fdw. The user, via a user interface, mayselectively allocate battery capacity among the voice functions fv andthe data functions fd according to the hierarchy. For example, the usermay specify maximum battery allocations C_(fv) and C_(fd) for the voiceand data functions fv and fd, maximum battery allocations C_(fva),C_(fvd), C_(fde), and C_(fdw) for the voice and data functions fva, fvd,fde, and fdw, or any combination thereof. Generally, the batterycapacity allocation for each function is less than or equal to that ofits associated parent function in the hierarchy. Thus, C_(fv)>C_(fva),C_(fvd) and C_(fd)>C_(fde), C_(fdw).

An illustrative allocation is provided in table 1 below. TABLE 1Hierarchical Allocation C_(fv) 60% C_(fva) 30% C_(fvd) 60% C_(fd) 40%C_(fde) 20% C_(fdw) 20%

According to the allocation of table 1, the voice functions fv areallocated 60% of the battery capacity, and the data functions areallocated 40% of the battery capacity. For the voice function allocationC_(fv), the analog voice function allocation C_(fva) is 30% and thedigital voice function allocation C_(fvd) is 60%. Accordingly, theanalog voice function fva may use only 30% of the battery capacity, andthe digital voice function may use up to 60% of the battery capacity.When the analog voice function fva has depleted 30% of the batterycapacity, the function is disabled. Likewise, when the digital voicefunction fva has depleted 60% of the battery capacity, the function isdisabled. Additionally, once the battery capacity depleted by the analogand digital voice functions fva and fvd totals 60%, all voice functionsfv are disabled.

Similarly, the e-mail data function allocation C_(fde) is 20%, and theweb browsing data function allocation C_(fdw) is also 20%. Accordingly,when the e-mail data function fde has depleted 20% of the batterycapacity, the function is disabled. Likewise, when the web browsing datafunction fdw has depleted 20% of the battery capacity, the function isdisabled. Once the battery capacity depleted by the data functions fdeand fdw totals 40%, all data functions fd are disabled.

FIG. 4 is a block diagram of another embodiment of the batterymanagement system 10. In this embodiment, the battery management module100 is operable to receive a power requirement 112 associated with eachsubsystem circuit or each subsystem function, and selectively to disablesubsystem circuits or functions when the present battery capacity cannotsupport the corresponding power requirements of the subsystem circuitsor functions.

The power requirements may be minimum power requirements or selectedpower requirements. A minimum power requirement specifies a minimumbattery capacity value required by the subsystem circuits or functionsto operate. For example, if a battery charge must be at least 10% of afull battery charge to enable the operation of a voice function fv, thenthe voice function has a minimum power requirement of 10%. The minimumpower requirements may be default values determined by the mobilecommunication device manufacturer, and stored in a memory such as aFlash memory or a ROM. Alternatively, the minimum power requirements maybe input by a user via the user interface 104.

A selected power requirement specifies a minimum battery capacity belowwhich the subsystem circuits or functions are precluded from operating.Although a function or its supporting subsystem circuits may be operablewhen battery capacity is below a selected requirement, the batterymanagement module 100 disables the function when the selected powerrequirement cannot be supplied. Where a voice function fv has a selectedpower requirement of 50%, then the voice function fv is selectivelydisabled when the battery charge falls below 50% of a full batterycharge. The selected power requirements may be default values selectedby the mobile communication device manufacturer and stored in a memorysuch as a Flash memory or a ROM, or input by a user via the userinterface 104.

FIG. 5 is a block diagram of another embodiment of the batterymanagement system 10. In this embodiment, the battery management module100 is operable to assign to each subsystem circuit and function abattery enable condition 1 14, to receive a battery condition signalfrom the battery monitoring circuit 102, and selectively to disable thesubsystem circuits and functions based on a comparison of thecorresponding battery enable condition to the present battery conditionsignal.

Battery enable conditions include, for example, a power requirement, asdescribed with respect to FIG. 4, a battery capacity allocation, asdescribed with reference to FIG. 2, and an enable temperature. In thelatter case, the battery monitoring circuit 102 provides a presentbattery temperature to the battery management module 100, and thebattery management module 100 is operable selectively to disable thesubsystem circuits or functions having corresponding enable temperaturesgreater than the present battery temperature.

As described above, when the battery temperature is low, such as duringa cold weather condition, the battery 30 tends to discharge morequickly, and lower power functions may thus be preferred over higherpower functions. Precluding operation of a subsystem circuit or functionhaving an enable temperature greater than the current batterytemperature prevents excessive discharge of the battery due to coldtemperature operation. In one embodiment, a battery enable temperatureis associated with each subsystem circuit. Generally, the battery enabletemperature is lower for subsystem circuits having a low powerrequirement. For example, a LCD display typically draws a current ofless than 1 milliamp, while a wireless communication subsystem typicallyrequires at least 200 milliamps to transmit data. Accordingly, the LCDdisplay may have a lower enable temperature than the communicationsubsystem.

Corresponding functions associated with each subsystem circuit having anenable temperature greater than the present battery temperature arelikewise disabled, as the required subsystems are precluded fromoperating. Each subsystem circuit is enabled as the present batterytemperature exceeds the subsystem circuit enable temperature. Once allrequired subsystem circuits for a particular function are enabled, theparticular function is then enabled. Functional status may be providedto the user via the user interface 104.

In another embodiment, a battery enable temperature is associated witheach function. This embodiment provides for a lower enable temperaturefor functions having a low power requirement or for functions having arelatively high power requirement of short duration. For example, akeyboard and display backlighting function, which may require 200milliamps, may have a relatively high enable temperature. An addressbook function, however, may have a relatively low enable temperature, asthe display, keyboard, processor and memory may draw only severalmilliamps during operation, provided backlighting of the display andkeyboard is precluded.

A data function fd may also have a relatively low enable temperature, asthe data function fd requires several hundred milliamps for a relativelyshort duration. For example, the communication subsystem S2 willtypically transmit a simple request, such as a Uniform ResourceIdentifier (URI) query during the execution of a data function fd, andwait to receive responsive data. The transmission of the URI query mayrequire only several hundred milliseconds (or less) of transmissiontime. Accordingly, the data function fd will not cause as significant abattery discharge as a corresponding voice function fv at the samebattery temperature. Furthermore, battery surface charge may initiallyprovide enough power to support the data function fd, which furtherlimits battery discharge.

The enable temperatures may be input by the user via a user interface104 or provided by the manufacturer of the mobile communication deviceand stored in a memory. Furthermore, the enable temperature may beadjusted for particular battery chemistries, such as Nickel MetalHydride (NiMH) batteries, Nickel Cadmium (NiCd) batteries, and LithiumIon (LiION) batteries. The LiION rechargeable battery, for example, hasa broader operating temperature range than the NiMH and NiCd batteries.Thus, the enable temperatures may be set lower for a LiION battery thanfor a NiMH or NiCd battery. For example, a voice function fv may have anenable temperature of 0° C. for a LiION battery, and an enabletemperature of 5° C. for a NiMH or NiCd battery.

The battery chemistry type may be input by the user or a default batterychemistry recommended by the manufacturer. If the enable temperaturesare also set by the manufacturer, then the enable temperatures mayinclude a first set of enable temperatures according to a recommendedbattery chemistry and additional sets of enable temperatures accordingto alternate battery chemistries. The enable temperatures used may thenbe later changed by the user if the user switches to a battery chemistrydifferent from the recommended battery chemistry. The user may specifythe battery chemistry via the user interface, or the battery may be asmart battery that includes circuitry that identifies the particularbattery chemistry to the mobile communication device.

In another embodiment, the battery is a smart battery and furtherincludes enable temperatures stored in a battery memory. Accordingly,the battery management module 100 receives the enable temperatures fromthe smart battery when the smart battery is connected to the mobilecommunication device.

FIGS. 6-10 are flow diagrams of battery management processes. The flowdiagrams may be implemented by software that is executable on aprocessing device in the mobile communication device 20 (FIG. 1), and bymonitoring and control circuitry. The software comprises instructionsthat cause the mobile communication device to perform the stepsdescribed below, and may be machine or object code, an interpretedlanguage, a script language, or even a platform independent language.Other types of software may also be used. Alternatively, the flowdiagrams may be implemented by digital logic elements, an ASIC module,or other hardware or firmware.

FIG. 6 is a flow diagram 200 of a battery management process based onbattery capacity allocation. At step 202, battery capacity is allocatedamong the subsystem circuits or functions to be controlled, inaccordance with either user inputs as described above or manufacturersettings read from memory. The battery capacities may be allocated tosubsystem circuits only, to functions only, or to both subsystemcircuits and functions.

Step 204 monitors the battery capacity depleted by each subsystemcircuit or function. The amount of battery capacity depleted by eachsubsystem circuit or function may be measured by milliamp hours, anamount of battery time, or other metric.

At step 206, the allocated battery capacity is compared to correspondingamounts of battery capacity depleted by each controlled subsystemcircuit or function. It is then determined at step 208 whether anysubsystem circuits or functions have depleted their allocatedcapacities. If no subsystem circuit or function has depleted itsallocated capacity, then steps 204 through 208 are repeated.

If a subsystem circuit or function has depleted its allocated capacity,however, then the subsystem circuit or function is disabled in step 210,and steps 204, 206 and 208 are repeated.

The subsystem circuits and functions may be disabled according theinterrelation of subsystem circuits and functions, as previouslydescribed.

FIG. 7 is a flow diagram 220 of a battery management process based onsubsystem circuit and function power requirements. Step 222 assignspower requirements for each subsystem circuit or function to becontrolled. Power requirements may be assigned to the subsystem circuitsonly, to the functions only, or to both the subsystem circuits and thefunctions. The power requirements may be assigned by the user or by themanufacturer and stored in memory in the mobile communication device 20.The power requirement may be a battery capacity, a minimum powerrequirement, or selected power requirement, as described above.

Step 224 monitors the present battery capacity. The monitoring step maybe carried out by the battery monitoring circuit 102, or mayalternatively be the result of battery data output by a smart battery.Other processes for monitoring the present battery capacity may also beused.

Step 226 determines whether the power requirement of each controlledsubsystem circuit or function exceeds the present battery capacity. Ifno subsystem circuit or function power requirements exceed the presentbattery capacity, then steps 224 and 226 are repeated.

If any of the power requirements exceed the present battery capacity,however. then the corresponding subsystem circuits or functions aredisabled in step 228, and steps 222 and 226 are repeated. The subsystemcircuits and functions may be disabled according to assigned powerrequirements and the interrelation of subsystem circuits and functions.For example, if the power requirements are assigned to subsystemcircuits only, then a function required to be supported by a disabledsubsystem circuit is preferably likewise disabled.

If the power requirements are assigned to functions only, however, thensubsystem circuits that support a disabled function will be precludedfrom operating to execute the disabled function. Such subsystem circuitsmay still be used to execute other supported and enabled functions,however. For example, if a voice function fv is disabled and a datafunction fd is enabled, a communication subsystem will be precluded fromoperating to execute the voice function fv, but will be allowed tooperate to execute the data function fd.

If the power requirements are assigned to both functions and subsystemcircuits, then the functions and subsystem circuits may be disabled bycombining the disabling routines described above.

FIG. 8 is a flow diagram 240 of a battery management process based onsubsystem circuit and function enable conditions. In step 242, an enablecondition is assigned for each subsystem circuit or function to becontrolled, Enable conditions may be assigned by a user or amanufacturer of a device to the subsystem circuits only, to thefunctions only, or to both the subsystem circuits and the functions.

Present battery condition is monitored at step 244. This monitoring stepmay be carried out by the battery monitoring circuit 102, or mayalternatively be the result of battery data output by a smart battery.Other processes for monitoring the present battery condition may also beused. At step 246, it is determined whether the subsystem circuit orfunction enable conditions are met based on the present batterycondition. If the subsystem circuit or function enable conditions aremet, then steps 244 and 246 are repeated. Where any of the subsystemcircuit or function enable conditions are not met, however, thecorresponding subsystem circuits or functions are disabled in step 248,and steps 244 and 246 are repeated. The subsystem circuits and functionsmay be disabled according to enable conditions and the interrelation ofsubsystem circuits and functions as previously described.

FIG. 9 is a flow diagram 260 of a battery management process based onfunction threshold temperatures. In this embodiment, the functions arecategorized according to voice functions and non-voice functions. Itshould be apparent that other categorizations may also be used.

A threshold temperature is assigned to the voice functions at step 262.The threshold temperature specifies a minimum battery temperature forexecution of the voice functions. The threshold temperature may beassigned by the user, assigned by the manufacturer and stored in memory,or stored as data in a smart battery, as described above.

At step 264, battery temperature is monitored. The present batterytemperature may be measured by the battery monitoring circuit 102 orprovided as data output by a smart battery. Where it is determined atstep 266 that the battery temperature is less than the thresholdtemperature, the voice functions are disabled in step 268, and theprocess returns to step 264.

If the battery temperature is not less than the threshold temperature,then step 270 determines if voice functions have been previouslydisabled. If voice functions have not been previously disabled, then theprocess returns to step 264. If voice functions have been previouslydisabled, however, then the voice functions are enabled in step 272, andthe process returns to step 264. Step 270 thus provides for reactivationof voice functions that have been previously disabled due to a coldbattery temperature.

FIG. 10 is a flow diagram 280 of a battery management process based onfunction threshold temperatures and battery chemistry. In thisembodiment, the enable temperatures may change based on batterychemistry.

A battery chemistry indicator is received at step 282. The batterychemistry indicator may be input by the user, stored as a defaultindicator by the manufacturer, or provided by a smart battery, asdescribed above. Step 284 assigns a threshold temperature to subsystemcircuits, functions, or both, based on the battery chemistry indicator.The assigned threshold temperatures may be one of several sets ofthreshold temperatures stored in a memory in the mobile communicationdevice, in which each set of threshold temperatures corresponds to aparticular battery chemistry. Alternatively, if the battery is a smartbattery or includes a memory device, then the threshold temperatures maybe stored in a memory device included in the battery and provided to thebattery management module 100.

The battery temperature is monitored at step 286. The present batterytemperature may be measured by the battery monitoring circuit 102 orprovided as data output by a smart battery, as described above. Step 288determines whether the battery temperature is less than the thresholdtemperatures. If the battery temperature is less than the thresholdtemperatures, then corresponding subsystem circuits and functions aredisabled in step 290, and the process returns to step 286.

If the battery temperature is not less than the threshold temperatures,then step 292 determines whether corresponding subsystem circuits andfunctions have been previously disabled. If corresponding subsystemcircuits and functions have not been previously disabled, then theprocess returns to step 286. If corresponding subsystem circuits andfunctions have been previously disabled, however, then the correspondingsubsystem circuits and functions are enabled in step 294, and theprocess returns to step 286.

Those skilled in the art to which the present invention pertains willappreciate that the flow diagrams in FIGS. 610 are intended forillustrative purposes. Battery management methods may include further,fewer, or different steps, than those shown in FIGS. 6-10, or performsteps in a different order than shown, without departing from the scopeof the present invention. For example, the various monitoring anddetermining steps may be substantially continuous, in that a particularcondition is monitored until some criterion is satisfied and furtheraction is taken. In FIG. 6, for example, battery capacity depletion maybe monitored until a subsystem circuit or function depletes itsallocated battery capacity, at which point the subsystem circuit orfunction is disabled. The monitoring either resumes after the subsystemcircuit or function has been disabled, or continues while the subsystemcircuit or function is being disabled.

In an alternative embodiment, the action of disabling a subsystemcircuit is dependent upon a user input. In this embodiment, a user isnotified that a subsystem circuit or function is about to be disabled,and is given a predetermined time period in which to take some action toavoid the subsystem circuit or function being disabled. The subsystemcircuit or function is then disabled either in response to a user inputto confirm that the subsystem circuit or function should be disabled, orafter the predetermined time period expires. Where the user selects an“Abort” or “Cancel Disable” function, or makes some other input to avoiddisabling the subsystem circuit or function before the predeterminedtime period expires, the subsystem circuit or function is not disabled.In an allocated capacity-based battery management scheme, a user may beprompted to re-allocate battery capacity or select from which otherallocation(s) the power required for the subsystem circuit or functionthat was to he disabled should be deducted. Alternatively, otherallocations can be reduced on an equal or pro-rata apportion scheme asdescribed above. This type of override feature is useful to preventinterruption of an important function when other subsystem circuits orfunctions have available allocated capacity. For example, a user maychoose to extend an urgent voice call at any cost to other functions, orto make use of battery capacity that has been allocated to a voicefunction for a data function when a communication network in which adevice is currently operating supports only data communications. Similarmanual override of other battery management schemes, such as to ignoreselected enable conditions, will be apparent to those skilled in theart.

FIG. 11 is a data structure 300 describing the interrelation ofsubsystem circuits, functions, and corresponding battery allocations,requirements, or conditions. The data structure 300 may be stored in amemory in a mobile communication device, or in some other computerreadable medium.

The data structure may comprise a database, an indexed file, or anyother data structure that describes the interrelation of subsystemcircuits, functions, and corresponding battery allocations,requirements, or conditions. In the embodiment of FIG. 11 a databasestructure is used, and the data structure 300 comprises a subsystemcircuit database 302, a function database 304, and a batteryallocation/requirement/condition database 306.

The subsystem circuit database 302 and the function database 304 specifythe interrelation of the subsystem circuits required to support a givenfunction. The battery allocation/requirement/condition database 306specifies the association of the battery allocations, requirements, orconditions to each subsystem circuit or function.

Accordingly, if the battery allocations, requirements or conditions areassociated with functions only, then the battery management module 100may preclude operation of corresponding subsystem circuits based on theinterrelation described by the subsystem circuit database 302 and thefunction database 304. Alternatively, if the battery allocations,requirements, or conditions are associated with subsystem circuits only,then the battery management module 100 may preclude operation of acorresponding function based on the interrelation described by thesubsystem circuit database 302 and the function database 304.

FIG. 12 is an exemplary display 400 illustrating remaining allocatedbattery capacity. The display 400 may be implemented in a mobilecommunication device, for example. Shown in the display 400 are a firstbattery indicator 402, a second battery indicator 404, and a thirdbattery indicator 406. The first battery indicator 402 corresponds toallocated battery capacity for a first function or set of functions,such as data functions. Likewise. the second battery indicator 404corresponds to allocated battery capacity for a second function or setof functions, such as voice functions. The third battery indicator 406corresponds to the total remaining battery capacity.

The lower region 408 of the display 400 is used to display variousfunction data, such as call data, web page data, and the like. Thebattery indicators 402, 404, and 406 may be displayed when a mobilecommunication device is in a standby mode, and may be removed during theperformance of functions to provide for additional display area fordisplaying function data.

Additional battery indicators may be displayed if the user has specifiedadditional allocations. Furthermore, each battery indicator 402 and 404may correspond to a node in a hierarchical allocation, such as thehierarchical allocation of FIG. 3. For example, the first batteryindicator 402 may correspond to the function node fd of FIG. 3, and thesecond battery indicator 404 may correspond to the function node fv ofFIG. 3. When hierarchical allocation is used, selection of a batteryindicator 402 or 404 may also cause battery indicators for functionsthat are lower in the hierarchy to be displayed. In the example of FIG.3, with the first and second battery indicators 402 and 404corresponding to fd and fv, respectively, selecting the batteryindicator 402 causes battery indicators for the functions fde and fdw tobe displayed. Likewise, selecting the second battery indicator 404causes battery indicators for functions fva and fvd to be displayed.

Thus, by allocating battery capacity among subsystem circuits orfunctions, the user may create “virtual batteries.” Depletion of onevirtual battery will preclude operation of functions associated withthat virtual battery, but will not preclude operation of functionsassociated with other virtual batteries that are not depleted.

The user may bypass or override the battery allocation at the user'sdiscretion, as described above. Furthermore, the battery allocation maybe temporarily disabled when the mobile communication device is poweredby an alternate power source, such as a recharging device. Additionally,during recharge, the battery allocations may be retained, and thus theuser need not reallocate battery capacity after each battery charge.

In another, different embodiment, a battery energy pool (e.g.,milliamp-hours) may be allocated and monitored. The energy pool can beassociated with subsystem circuits or functions, and monitored andcompared to the present expenditure of battery energy. The activation ofthe subsystem circuits or functions can be based on the comparison. Forexample, the activation of the subsystem circuits or functions mayinvolve disabling the subsystem circuits or functions when the expendedenergy exceeds the energy pool.

Conversely, all other unrelated subsystem circuits or functions may bedisabled when the expended energy exceeds the energy pool. For example,an energy pool may be allocated to an emergency service call, such as a911 call, If the expended energy exceeds the energy pool, then all othersubsystem circuits and functions not related to the emergency service(e.g., calendar functions, ring adjustment functions and related I/Ocircuitry, etc.) may be disabled to conserve battery energy for theemergency service.

FIG. 13 is a block diagram of an exemplary mobile communication device900 in which the systems and methods disclosed herein may beimplemented. The wireless device 900 is preferably a two-waycommunication device having at least voice and data communicationcapabilities. The voice communications may be implemented over either ananalog or digital voice communication channel. The device preferably hasthe capability to communicate with other computer systems on theInternet. Depending on the functionality provided by the device, thedevice may be referred to as a data messaging device, a two-way pager, acellular telephone with data messaging capabilities, a wireless Internetappliance or a data communication device (with or without telephonycapabilities).

Where the device 900 is enabled for two-way communications, the devicewill incorporate a communication subsystem 91 1, including a receiver912, a transmitter 914, and associated components such as one or more,preferably embedded or internal, antenna elements 916 and 918, localoscillators (LOs) 913, and a processing module such as a digital signalprocessor (DSP) 920. The particular design of the communicationsubsystem 911 will be dependent upon the communication network in whichthe device is intended to operate. For example, a device 900 destinedfor a North American market may include a communication subsystem 911designed to operate within the Mobitex mobile communication system orDataTAC mobile communication system, whereas a device 900 intended foruse in Europe may incorporate a General Packet Radio Service (GPRS)communication subsystem 911.

Network access requirements will also vary depending upon the type ofnetwork 919. For example, in the Mobitex and DataTAC networks, mobiledevices such as 900 are registered on the network using a uniquepersonal identification number or PIN associated with each device. InGPRS networks, however, network access is associated with a subscriberor user of a device 900. A GPRS device, therefore, requires a subscriberidentity module (not shown), commonly referred to as a SIM card, inorder to operate on a GPRS network. Without a SIM card, a GPRS devicewill not be fully functional. Local or non-network communicationfunctions (if any) may be operable, but the device 900 will be unable tocarry out any functions involving communications over network 919. Whenrequired network registration or activation procedures have beencompleted, a device 900 may send and receive communication signals overthe network 919. Signals received by the antenna 916 through acommunication network 919 are input to the receiver 912, which mayperform such common receiver functions as signal amplification,frequency down conversion, filtering, channel selection and the like,and in the example system shown in FIG. 13, analog to digitalconversion. Analog to digital conversion of a received signal allowsmore complex communication functions, such as demodulation and decoding,to be performed in the DSP 920. In a similar manner, signals to betransmitted are processed, including modulation and encoding, forexample, by the DSP 920 and input to the transmitter 914 for digital toanalog conversion, frequency up conversion, filtering, amplification andtransmission over the communication network 919 via the antenna 918.

The DSP 920 not only processes communication signals, but also providesfor receiver and transmitter control. For example, the gains applied tocommunication signals in the receiver 912 and transmitter 914 may beadaptively controlled through automatic gain control algorithmsimplemented in the DSP 920.

The device 900 preferably includes a microprocessor 938, which controlsthe overall operation of the device. Communication functions, includingat least data and voice communications, are performed through thecommunication subsystem 911. The microprocessor 938 also interacts withfurther device subsystems, such as the display 922, Flash memory 924,random access memory (RAM) 926, auxiliary input/output (I/O) subsystems928, serial port 930, keyboard 932, speaker 934, microphone 936, ashort-range communications subsystem 940, a power subsystem 942, and anyother device subsystems generally designated as 944.

Some of the subsystems shown in FIG. 13 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 932 and display922, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork and device-resident functions such as a calculator or task list,Operating system software used by the microprocessor 938 is preferablystored in Flash memory 924, which may instead be a battery backed-up RAMor other non-volatile storage element. The operating system, specificdevice applications, or parts thereof, may be temporarily loaded into avolatile store such as RAM 926. Received communication signals may alsobe stored to RAM 926. Flash memory 924 preferably includes datacommunication module 924B when device 900 is enabled for datacommunications, and when device 900 is enabled for voice communication,a voice communication module 924A. Also included in Flash memory 924 areother software modules 924N. In particular, the battery managementsystem 20 software may be implemented in a software module, such assoftware module 924N.

The microprocessor 938, in addition to its operating system functions,preferably enables execution of software applications on the device. Apredetermined set of applications that control basic device operations,including at least data and voice communication applications, forexample, will normally be installed on the device 900 duringmanufacture. A preferred application that may be loaded onto the devicemay be a personal information manager (PIM) application having theability to organize and manage data items relating to the device user,such as, but not limited to, e-mail, calendar events, voice mails,appointments, and task items. Naturally, one or more memory stores wouldbe available on the device to facilitate storage of PIM data items onthe device. Such PIM application would preferably have the ability tosend and receive data items via the wireless network. In a preferredembodiment, the PIM data items are seamlessly integrated, synchronizedand updated, via the wireless network, with the device user'scorresponding data items stored or associated with a host computersystem.

Further applications may also be loaded onto the device 900 through thenetwork 919, an auxiliary I/O subsystem 928, serial port 930,short-range communications subsystem 940 or any other suitable subsystem944, and installed by a user in the RAM 926 or a non-volatile store forexecution by the microprocessor 938. Such flexibility in applicationinstallation increases the functionality of the device and may provideenhanced on-device functions, communication-related functions, or both.For example, secure communication applications may enable electroniccommerce functions and other such financial transactions to be performedusing the device 900.

In a data communication mode, a received signal such as a text messageor web page download will be processed by the communication subsystem911 and input to the microprocessor 938, which will preferably furtherprocess the received signal for output to the display 922, oralternatively, to an auxiliary I/O device 928. A user of device 900 mayalso compose data items, such as e-mail messages, for example, using thekeyboard 932, which is preferably a complete alphanumeric keyboard ortelephone-type keypad, in conjunction with the display 922 and possiblyan auxiliary I/O device 928. Such composed items may then be transmittedover a communication network through the communication subsystem 911.

For voice communications, overall operation of the device 900 issubstantially similar, except that received signals would preferably beoutput to a speaker 934 and signals for transmission would be generatedby a microphone 936. Alternative voice or audio I/O subsystems, such asa voice message recording subsystem, may also be implemented on thedevice 900. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 934, the display 922 may alsobe used to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information, forexample.

Depending on the enable condition, a particular function associated witha subsystem circuit may be disabled, or an entire subsystem circuit maybe disabled. For example, if the battery temperature is low, then voicefunctions may be disabled, but data communications, such as e-mail, maystill be enabled over the communication subsystem 911.

The serial port 930 would normally be implemented in a personal digitalassistant (PDA)-type communication device for which synchronization witha user's desktop computer (not shown) may be desirable, but is anoptional device component. Such a port 930 would enable a user to setpreferences through an external device or software application and wouldextend the capabilities of the device by providing for information orsoftware downloads to the device 900 other than through a wirelesscommunication network. The alternate download path may, for example, beused to load an encryption key onto the device through a direct and thusreliable and trusted connection thereby to enable secure devicecommunication.

A short-range communications subsystem 940 is a further optionalcomponent which may provide for communication between the device 900 anddifferent systems or devices, which need not necessarily be similardevices. For example, the subsystem 940 may include an infrared deviceand associated circuits and components or a Bluetooth™ communicationmodule to provide for communication with similarly-enabled systems anddevices

A power subsystem 942 comprises a battery and power distribution andrecharge circuitry for providing battery power to the mobile device 900and for recharging the battery. The power subsystem 942 also includes abattery monitoring circuit that is operable to provide a status of oneor more battery status indicators, such as remaining capacity,temperature, voltage, current draw, and the like. The battery statusindicators may provided to the microprocessor in digital form.

This written description uses illustrative embodiments to disclose theinvention, including the best mode, and also to enable a person ofordinary skill in the art to make and use the invention. Otherembodiments and devices are within the scope of the claims if they haveelements that do not differ from the literal language of the claims orhave elements equivalent to those recited in the claims.

For example, the invention is not limited to monitoring only thosebattery characteristics described above. In an alternative embodiment,aging effects such as variations in battery chemistry are estimated andused to allocate battery capacity. Aging tends to increase equivalentseries resistance (ESR), for instance, which reduces the capacity thatcan be used effectively for higher power functions or subsystems.

1. A battery management system for managing a plurality of subsystems ofa mobile communication device powered by a battery, comprising: meansfor monitoring a present battery condition of the battery; means forcomparing the present battery condition with an enable condition of theplurality of subsystems to determine if a disable condition has beenmet; and means for selectively disabling a subsystem in the plurality ofsubsystems if the disable condition has been met for the subsystem. 2.The battery management system of claim 1, wherein the enable conditionis an allocation of battery capacity associated with the subsystems, thepresent battery condition is the amount of battery capacity depleted bythe subsystems, and the disable condition is met when the depletedamount of battery capacity exceeds the allocation of battery capacityfor a subsystem.
 3. The battery management system of claim 1, whereinthe enable condition is a power requirement associated with thesubsystems, the present battery condition is a battery capacitymeasurement, and the disable condition is met when the power requirementexceeds the measured battery capacity for a subsystem.
 4. The batterymanagement system of claim 1, wherein the enable condition is athreshold temperature associated with the subsystems, the presentbattery condition is a battery temperature measurement, and the disablecondition is met when the battery temperature is less than the thresholdtemperature for a subsystem.
 5. The battery management system of claim4, further comprising: means for receiving a battery chemistryindicator; and means for associating the threshold temperature enableconditions for the subsystems as a function of the received batterychemistry indicator.
 6. The battery management system of claim 2,further comprising: means for displaying a battery allocation indicatorfor at least one of the plurality of subsystems on a display of themobile device.
 7. The battery management system of claim 2, furthercomprising: means for allocating battery capacity associated with thesubsystems.
 8. The battery management system of claim 7, wherein themeans for allocating battery capacity comprises a means for associatinga plurality of mobile device functions with the subsystems and a meansfor hierarchically allocating battery capacity among the mobile devicefunctions.
 9. The battery management system of claim 1, furthercomprising: means for notifying the user of the mobile communicationdevice that a subsystem is about to be selectively disabled if thedisable condition has been met; and means for enabling the user of themobile communication device to abort the selective disabling of thesubsystem.
 10. The battery management system of claim 9, furthercomprising: means for modifying the enable condition of the subsystem inresponse to aborting the selective disabling of the subsystem.
 11. Thebattery management system of claim 1, further comprising: means fortemporarily disabling the selectively disabling of a subsystem inresponse to the mobile communication device being coupled to analternate power source than the battery.
 12. A method for managing aplurality of subsystems in a mobile communication device having abattery, comprising: monitoring a present condition of the battery;comparing the present battery condition with an enable condition of theplurality of subsystems to determine if a disable condition has beenmet; and disabling a subsystem in the plurality of subsystems if thedisable condition has been met for the subsystem.
 13. The method ofclaim 12, wherein the enable condition is an allocation of batterycapacity associated with the subsystems, the present battery conditionis the amount of battery capacity depleted by the subsystems, and thedisable condition is met when the depleted amount of battery capacityexceeds the allocation of battery capacity for a subsystem.
 14. Themethod of claim 12, wherein the enable condition is a power requirementassociated with the subsystems, the present battery condition is abattery capacity measurement, and the disable condition is met when thepower requirement exceeds the measured battery capacity for a subsystem.15. The method of claim 12, wherein the enable condition is a thresholdtemperature associated with the subsystems, the present batterycondition is a battery temperature measurement, and the disablecondition is met when the battery temperature is less than the thresholdtemperature for a subsystem.
 16. The method of claim 15, furthercomprising;: identifying a battery chemistry indicator; and associatingthe threshold temperature enable conditions for the subsystems as afunction of the battery chemistry indicator.
 17. The method of claim 13,further comprising: displaying a battery allocation indicator for atleast one of the plurality of subsystems on a display of the mobiledevice.
 18. The method of claim 13, further comprising: allocatingbattery capacity associated with the subsystems.
 19. The method of claim18, wherein the allocating act further comprises associating a pluralityof mobile device functions with the subsystems and hierarchicallyallocating battery capacity among the mobile device functions.
 20. Themethod of claim 12, further comprising: notifying the user of the mobilecommunication device that a subsystem is about to be disabled if thedisable condition has been met; and enabling the user of the mobilecommunication device to abort the disabling of the subsystem.
 21. Themethod of claim 20, further comprising: modifying the enable conditionof the subsystem in response to aborting the disabling of the subsystem.22. The method of claim
 12. further comprising: temporarily disablingthe disabling of a subsystem in response to the mobile communicationdevice being coupled to an alternate power source than the battery. 23.A mobile communication device, comprising a battery for supplying powerto a plurality of subsystems of the mobile communication device; and abattery monitoring circuit for monitoring a present battery condition ofthe battery; and a battery management module for comparing the presentbattery condition with an enable condition of the plurality ofsubsystems to determine if a disable condition has been met, and forselectively disabling a subsystem in the plurality of subsystems if thedisable condition has been met for the subsystem.
 24. The mobilecommunication device of claim
 23. further comprising: a voice subsystemfor transmitting and receiving voice calls; and a data subsystem fortransmitting and receiving data calls; wherein the enable condition forthe voice subsystem and the data subsystem is an allocation of batterycapacity associated with the subsystems, the present battery conditionis the amount of battery capacity depleted by the subsystems, and thedisable condition is met when the depleted amount of battery capacityexceeds the allocation of battery capacity for a subsystem.
 25. Themobile communication device of claim 24, wherein the allocation ofbattery capacity for the voice and data subsystems is input to themobile communication device by a user.